A disc cartridge holding a disc-shaped recording medium, such as a magnetic disc or a magneto-optical disc, has its main cartridge body portion combined from paired upper and lower cartridge halves, and a disc-shaped recording medium is rotatably housed in a disc housing section formed in the main cartridge body portion.
In the main cartridge body portion, recording/reproducing apertures are formed facing each other for exposing a portion of the signal recording area of the disc-shaped recording medium held in the disc housing section to outside across the inner and outer rims of the disc, and into which is intruded recording/reproducing means provided on a recording/reproducing apparatus. A shutter member is mounted on the main cartridge body portion for opening/closing these recording/reproducing apertures.
In the lower cartridge half constituting the lower surface of the main cartridge body portion is formed a circular center opening into which is intruded a turntable of the recording/reproducing apparatus. This center opening permits a center hub mounted at the center of the disc-shaped recording medium housed in the main cartridge body portion to be exposed to outside from the lower cartridge half.
On the inner surfaces of the main cartridge body portion are arranged protective sheets of, for example, a non-woven fabric, for protecting the disc-shaped recording medium housed therein. These protective sheets are arranged in the inner surfaces of the main cartridge body portion for sandwiching the disc-shaped recording medium in-between.
The inner surfaces of the upper and lower cartridge halves, making up the main cartridge body portion, are provided with plural fitting recesses and projections which are interengaged and ultrasonically welded to one another by ultrasonic welding means to complete a unified main cartridge body portion. These ultrasonic welding means generate mechanical vibrations on the abutting surfaces of the fitting recesses and projections to fuse the abutment surfaces by the heat of friction generated by mechanical vibrations.
In keeping up with recent tendency towards multi-media, the information signals, such as picture data or speech data, are diversified and increased in volume, thus increasing the recording capacity of the disc cartridge. For recording the information signals of the increased volume, there is proposed a disc cartridge having an increased recording density for information signals.
The main cartridge body portion housing the disc-shaped recording medium, such as the disc cartridge, is produced by interconnecting the upper and lower cartridge halves by ultrasonic welding means, so that contaminants, such as dust and dirt, are produced from the protective sheets, such as non-woven cloths, provided on the inner surfaces of the main cartridge body portion, or the upper and lower cartridge halves.
With the disc-shaped recording medium, increased in recording density, if dust and dirt of the smallest size become affixed to the signal recording area, recording and/or reproducing errors are produced at the time of recording and/or reproduction of information signals.